P2 Short form for Professional Plug-In, P2 is a professional digital video storage media format introduced by Panasonic in 2004, and especially tailored to ENG applications. It features tapeless (non-linear) recording of DVCPRO, DVCPRO50, DVCPRO-HD, or AVC-Intra streams on a solid state flash memory card. The P2 Card is essentially a RAID of SD memory cards with an LSI controller tightly packaged in a PC card (formerly PCMCIA) enclosure, so data transfer rate increases as memory capacity increases. See DV, ENG
Pack A set of clips, mattes and settings for DVE, color corrector, keyer, etc., that are used together to make a video layer in a composited picture.
PAL Phase Alternating Line. The analog color coding system for television widely used in Europe and throughout the world, almost always with the 625 line/50 field system. It was derived from the NTSC system but by reversing the phase of the reference color burst on alternate lines (Phase Alternating Line) is able to correct for hue shifts caused by phase errors in the transmission path. Bandwidth for the PAL-I system is typically 5.5 MHz luminance, and 1.3 MHz for each of the color difference signals, U and V. Note that the PAL term is frequently used to describe any 625/50I analog format - even if it is component, or in the 576/50I digital television system where PAL coding is not used.
PAL-M A version of the PAL standard, but using a 525 line 60-field structure. Used only in parts of South America (e.g. Brazil).
PAN Personal area network used for communicating between computer-based devices, such as phones, mobile TVs and PDAs as well as fixed computers - all within a few meters - and through to other networks - such as The Internet. PANs can be wired, via busses such as USB or IEEE 1394, or wireless (WPAN) using technologies such as Bluetooth.
Parallel processing Using several processors simultaneously with the aim of increasing speed over single processor performance. It often refers to array processor computer hardware that carries out multiple, often identical, mathematical computations at the same time.
Parallax (Stereoscopic) This refers to the separation of the left and right images on the projection device or display screen. Positive Parallax puts an object behind the screen (on screen objects in the left eye image are to the left of the same objects in the right eye image). Negative parallax puts an object in front of the screen (on screen objects in the left eye image are to the right of the same objects in the right eye image). Zero or neutral parallax puts an object on the screen (on screen objects in the left eye image are overlaid on the same objects in the right eye image). The only difference between stereo cameras should be parallax or angle between the axes of the lenses, as in Camera Convergence - anything else can disturb the stereo viewing experience. This requires close attention, so that the cameras are set-up the same and with the same filters. Color differences, skewing, vertical misalignment, differential weave and hop, lens flares, poor VFX fixes, scratches and dirt can all cause problems. Fast cuts between shots with strong positive and strong negative parallax can be unsettling in some circumstances. This is because the eyes and brain are being asked to jump uncomfortably quickly between positions and then make sense of the result. This can be mitigated by the use of 'handing off' - dynamically changing the convergence of an outgoing shot in relation to an incoming shot. Another method of dealing with this is trying wherever possible to cut between shots that are somewhat close in parallax. Vertical parallax is a vertical offset between stereo images and is very uncomfortable to watch - so it is necessary to remove it during post production if there has been camera misalignment during shooting. Note: The term 'Parallax' is sometimes used interchangeably with 'Congruence' or 'Disparity'
Perf Short for perforations. It is a way to describe some information about the format of images on 35mm film by how many of the perforations, or sprocket holes, are used per image. For example, Full Frame is 4 perf.
P-frames See MPEG-2
Photo-real Video and film effects that are constructed in such a way that they look totally real and not synthetic are referred to as photo-real effects. This use of effects has increased rapidly and has changed the way many productions are shot and post produced - leading to lower budgets and better looking results. Achieving photo-real results requires careful planning from the shoot and computer imagery through to compositing in post production. Excellence in keying, so there are no telltales of blue screen haloes or color spill, are among the many techniques required for successful results. See also: Compositing, Digital keying
Pixel (or Pel) A shortened version of 'Picture cell' or 'Picture element'. The name given to one sample of picture information. Pixel can refer to an individual sample of R, G, B, luminance or chrominance, or sometimes to a collection of such samples if they are co-sited and together produce one picture element. See also: Aspect ratio - of pixels, Sub-pixel
PLD Programmable Logic Device. This is a family of devices that has included PROMs (Programmable Read Only Memories), PLAs (Programmable Logic Arrays) and PALs (Programmable Array Logic). Today FPGAs (Field Programmable Gate Arrays) are the main interest. These range in size and complexity from a few dozen up to millions of gates to provide a compact and efficient means of implementing complex non-standard logic functions. See also: Moore 's Law
Plug-in Software, usually from a third party, that brings added functionality to a computer application. For post production this may add highly specialized aspects to digital effects.
POTS Plain Old Telephone Service. This is the analog connection that many people still speak on, or connect their modems or fax machines to. Its applications have gone far beyond its initial aims.
Printer lights The illumination used to expose film in a processing laboratory. 'White' light is passed through red, blue and green filters so that the exposure to each can be individually controlled. Film is contact printed, placing the new film stock against the processed film that carries the images. The amount of light can be varied to provide the required exposure to show more detail in the highlights or the shadows or to keep to the mid-range of the scene brightness. To print an overexposed negative will require higher values and underexposed lower values of printer lights. A change of 1 in the value represents 1/12th of a stop adjustment in exposure. Differential adjustments of the values provides basic color correction (timing). The values for the lights are recorded as grading (timing) numbers onto disk or paper tape. See also: Color timing, Film Basics (Tutorial 2), One-light pass, Timing
Print film Film stock designed specifically for distribution and exhibition at cinemas. Unlike negative film, it is high contrast and low on latitude. This is designed to give the best performance when viewed at cinemas. Obviously a release print has to be clear of the orange base so this is bleached out during processing. See also: Film basics (Tutorial 2)
Profile See MPEG-2
Progressive (scan) Method of scanning lines down a screen where all the lines of a picture are displayed in one continuous vertical scan (progression). There are no fields or half pictures as with interlace scans. Progressive scanning is becoming far more common as it is used with computer displays and all panel displays - LCD and Plasmas, and is now starting to be used for some DTV formats, e.g. - 1080/24P, 720/60P. The 'P' denotes progressive. A high picture refresh rate is required to give good movement portrayal, such as for fast action and camera pans. For television applications using progressive scanning, this implies a high bandwidth or data rate and high scanning rates on CRT displays. Progressive scanning does not show the dither of detail associated with interlaced scans. See also: 24P, Interlace, Interlace Factor
Projectors (digital) Digital projectors input digital images and project them onto cinema-sized screens. Huge advances in this technology in recent years have been one of the driving forces behind digital cinema. For post production or DI, many houses offer big screens for customers to see what the final cinema experience will look like. With resolutions up to 4K, the viewing public is very impressed with the results as, without film's scratches, dirt and weave, they are treated to consistent high quality results. Combined with suitable digital cinema players some projectors can sequentially display the left and right-eye images of stereo movies for a 3D film experience. See also: Color management, Digital Cinema, DLP, D-ILA, SXRD
Pseudoscopic (Stereoscopic) If a stereoscopic signal is reversed (e.g. each eye is being fed the opposite eye signal) a strange 'punched in' effect appears. This is also referred to as inverted stereo or reversed stereo.
Publishing See Deliverables
Pulfrich effect (Stereoscopic) Horizontal motion that can be interpreted as binocular depth. A stereo effect which is produced when 2D images moving laterally on a single plane are viewed at slightly different times by each eye.
Purpose-built hardware Hardware and software built for a specific task (e.g. a DVE), not general purpose (computer). Purpose-built hardware is able to provide much improved processing speeds, between 10 and 100 fold, over systems using the same technology applied to general-purpose architecture and operating system software.